Service request processing

The present disclosure generally relates to the technical field of telecommunication, and particularly to methods and Network Function (NF) nodes for processing a service request in a network comprising a set of NF nodes, and a corresponding computer readable medium.

This section is intended to provide a background to the various embodiments of the technology described in this disclosure. The description in this section may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and/or claims of this disclosure and is not admitted to be prior art by the mere inclusion in this section.

In Fifth Generation (5G) networks, a Network Slice is introduced as a logical network that provides specific network capabilities and network characteristics. An instance of a network slice (e.g. a network slice instance (NSI)) is a set of Network Function (NF) instances and the required resources (e.g., computing, storage, and networking resources) which form a deployed Network Slice. An NF is a third generation partnership project (3GPP) adopted or 3GPP defined processing function in a network, which has defined functional behavior and 3GPP defined interfaces. An NF can be implemented either as a network element on dedicated hardware, a software instance running on a dedicated hardware, or as a virtualized function instantiated on an appropriate platform, e.g., on a cloud infrastructure.

Among the NFs, a Service Communication Proxy (SCP) is defined, which provides centralized capabilities such as Service Based Interface (SBI) routing, NF discovery and selection, failover, message screening, etc. An SCP is used in indirect routing scenarios and one of the options to deploy SCP is model D, as described in 3GPP technical standard (TS) 23.501 (see, for example, annex E of 3GPP TS 23.501).

1 FIG. shows a communication model for NF/NF services interaction in model D, as described in 3GPP TS 23.501.

As per the service definition in 3GPP 23.501, Model D can be defined as indirect communication with delegated discovery. That is, NF service consumers do not do (perform) any discovery or selection. The consumer adds any necessary discovery and selection parameters required to find a suitable producer to a service request. The SCP uses a request address and the discovery and selection parameters in a request message to route the request to a suitable producer instance. The SCP can perform discovery with a Network Repository Function (NRF) and obtain a discovery result.

In this model, the SCP discovers the target NF service producer. As per the service definition in 3GPP 23.501, if indirect communication with delegated discovery is used, the NF service consumer sends the request to the SCP and provides, within the service request to the SCP, the discovery and selection parameters necessary to discover and select an NF service producer.

Moreover, it is indicated in 3GPP TS 29.501 that an Application Program Interface (API) version is part of a resource Uniform Resource Identifier (URI). Clause 4.3.1.3 of 3GPP TS 29.501 relates to the visibility of the API version number fields. The API version can be indicated in the resource URI of every API, as described in clause 4.4.1 of 3GPP TS 29.501. The API version can be indicated as the concatenation of the letter “v” and the 1st field of the API version number. The other fields may not be included in the resource URI. Including these digits in the URI can force the NF service consumer to select a specific sub-version, at the risk of seeing the request rejected if the NF service provider does not support it, while the request may have been served by ignoring unknown elements.

{apiRoot}/<apiName>/<apiVersion>/<apiSpecificResourceUriPart> Clause 4.4.1 of 3GPP TS 29.501 relates to a resource URI structure. Resources are either individual resources, or structured resources that can contain child resources. It is commonly recommended to design each resource following one of the archetypes provided in Annex C of 3GPP TS 29.501. A URI uniquely identifies a resource. In the 5G core (5GC) SBI APIs, when a resource URI is an absolute URI, its structure can be specified as follows:

“apiName” defines the name of the API and “apiVersion” indicates the 1st Field (MAJOR) of the version of the API (see, for example, clause 4.3.1.3 and 4.4.1 of 3GPP TS 29.501). In clause 4.3.1.1 of 3GPP TS 29.501, an API version number format is also indicated. API version numbers can consist of at least 3 fields, following a MAJOR.MINOR.PATCH pattern (for example, according to the Semantic Versioning Specification).

Two versions that differ in the major field or even in the minor field can have backward incompatible changes.

There is an issue when there are NFs deployed with different versions that are non-backward-compatible (NBC) or where there are NFs deployed with NBC versions among them. Even though NBC versions are usually minimized, it will be common that, for each API, NBC versions arise. There are already some cases such as, for example, a Policy Control Function (PCF) API.

With indirect communication with delegated discovery (model D), an NF service consumer does not perform NRF discovery to get (acquire) the profiles of NF service producers. Instead, this discovery is delegated to the SCP. When the NF service consumer receives an error response from the SCP for a service request, it does not know the failure reason, and thus cannot retry a service request by addressing the failure.

At least some objects of the present disclosure are to provide technical solutions capable of allowing NF service consumers to be aware of failure reasons for a service request and retry a service request if it supports multiple NF service producer NBC API versions.

According to a first aspect of the present disclosure, there is provided a method performed at a first network function (NF) node for requesting a service with an SCP. The method comprises transmitting a request for the service to the SCP, the request comprising at least an indication indicating a required API version for the service, wherein the required API version is other than an API version included in a Resource Uniform Resource Identifier, URI, in the request.

In an exemplary embodiment, the method may further comprise receiving, from the SCP, a response including an error message indicating that no second NF node provides the required API version for the service.

In an exemplary embodiment, the response may further include information on an API version for the service of at least one second NF node that provides an API version different from the required API version for the service.

In an exemplary embodiment, the method may further include constructing a different request for the service by changing the required API version.

In an exemplary embodiment, constructing a different request for the service may be performed by taking the received information on the different API version into account.

In an exemplary embodiment, the required API version only indicates a major version.

According to a second aspect of the present disclosure, there is provided a method performed at an SCP. The method comprises receiving a request for a service from a first NF node, the request including an indication indicating a required API version for the service, wherein the required API version is other than an API version included in a Resource URI in the request; and searching for a second NF node that provides the service of the required API version.

In an exemplary embodiment, searching for a second NF node may comprise transmitting, to a Network Repository Function (NRF) an NF discovery request for discovering a second NF node that provides the required API version for the service; or searching in a cache of the SCP for the second NF node.

In an exemplary embodiment, the method may further comprise transmitting a response to the first NF node, including an error message indicating that no second NF node provides the required API version for the service.

In an exemplary embodiment, the method may further comprise searching for at least one second NF node that provides the service of an API version different from the required API version.

In an exemplary embodiment, the method may further comprise including information on the different API version for the service of the at least one second NF node, if any, in the response to the first NF node.

In an exemplary embodiment, the method may further comprise extracting the information on the different API version from a profile of the at least one second NF node.

In an exemplary embodiment, the required API version may only indicate a major version.

According to a third aspect of the present disclosure, there is provided a method performed at an SCP. The method comprises receiving a request for a service from a first NF node; extracting an API version from a Resource URI in the request, as a required API version for the service; and searching for a second NF node that provides the service of the required API version.

In an exemplary embodiment, searching for a second NF node may comprise transmitting, to an NRF an NF discovery request for discovering a second NF node that provides the required API version for the service; or searching in a cache of the SCP for the second NF node.

In an exemplary embodiment, the method may further comprise transmitting a response to the first NF node, including an error message indicating that no second NF node provides the required API version for the service.

In an exemplary embodiment, the method may further comprise searching for at least one second NF node that provides the service of an API version different from the required API version.

In an exemplary embodiment, the method may further comprise including information on the different API version for the service of the at least one second NF node, if any, in the response to the first NF node.

In an exemplary embodiment, the method may further comprise extracting the information on the different API version from a profile of the at least one second NF node.

According to a fourth aspect of the present disclosure, a first NF node is provided. The first NF node comprises at least one processor configured to operate in accordance with the above-described first aspect. In some embodiments, the first NF node may comprise a communication interface arranged for communication. In some embodiments, the first NF node may comprise a memory comprising instructions which, when executed by the at least one processor, cause the first NF node to perform the above-described first aspect.

According to a fifth aspect of the present disclosure, an SCP is provided. The SCP comprises at least one processor configured to operate in accordance with the above-described second aspect and/or third aspect. In some embodiments, the SCP may comprise a communication interface arranged for communication. In some embodiments, the SCP may comprise a memory comprising instructions which, when executed by the at least one processor, cause the SCP to perform the above-described second aspect and/or third aspect.

According to a sixth aspect of the present disclosure, there is provided a computer program comprising instructions which, when executed by at least one processor, cause the at least one processor to perform the method according to the above-described first aspect, second aspect, and/or third aspect.

According to a seventh aspect of the present disclosure, there is provided a carrier containing the computer program discussed above. In some embodiments, the carrier may be one of an electronic signal, optical signal, radio signal, or computer readable storage medium.

According to an eighth aspect of the present disclosure, there is provided a computer readable storage medium having computer program instructions stored thereon, the computer program instructions, when executed by at least one processor, causing the processor to perform the method according to the above-described first aspect, second aspect, and/or third aspect.

According to the above technical solutions of the present disclosure, the NF service consumer may know the failure reason when receiving an error response for a service request. Thus, the SCP may provide additional API versions to the NF service consumer in case there is no NF service producer that provides the required version, the NF service consumer may retry a service request by using the additional API versions if supported. Therefore, there is provided herein a solution to support multiple NF service producer NBC API versions with indirect communication, e.g. with model D.

It should be noted that throughout the drawings, same or similar reference numbers are used for indicating same or similar elements; various parts in the drawings are not drawn to scale, but only for an illustrative purpose, and thus should not be understood as any limitations and constraints on the scope of the present disclosure.

Hereinafter, the principle and spirit of the present disclosure will be described with reference to illustrative embodiments. Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art.

1) 3GPP TS 23.501, V17.3.0 (2021 December), 2) 3GPP TS 29.501, V17.4.1 (2021 December), and 3) 3GPP TS 29.510, V17.4.0 (2021 December). Additional information may also be found in references as follows:

References in this specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc. indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of the person skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “has”, “having”, “includes” and/or “including”, when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

th The techniques described herein may be used for various wireless communication networks such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier-Frequency Division Multiple Access (SC-FDMA), Long Term Evolution (LTE), New Radio (NR) and other networks developed in the future. The terms “network” and “system” are sometimes used interchangeably. For illustration only, certain aspects of the techniques are described below for the 5generation of wireless communication network. However, it will be appreciated by the person skilled in the art that the techniques described herein may also be used for other wireless networks such as LTE and corresponding radio technologies mentioned herein as well as wireless networks and radio technologies proposed in the future.

As used herein, the term “UE” may be, by way of example and not limitation, a User Equipment (UE), a SS (Subscriber Station), a Portable Subscriber Station (PSS), a Mobile Station (MS), a Mobile Terminal (MT) or an Access Terminal (AT). The UE may include, but is not limited to, mobile phones, cellular phones, smart phones, or personal digital assistants (PDAs), portable computers, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, wearable terminal devices, vehicle-mounted wireless terminal devices and the like. In the following description, the terms “UE”, “terminal device”, “mobile terminal” and “user equipment” may be used interchangeably.

2 FIG. illustrates a wireless communication system represented as a 5G network architecture composed of core NFs, where interaction between any two NFs is represented by a point-to-point reference point/interface.

2 FIG. 2 FIG. Seen from the access side, the 5G network architecture shown incomprises a plurality of User Equipment (UEs) connected to either a Radio Access Network (RAN) or an Access Network (AN) directly, as well as an Access and Mobility Management Function (AMF) indirectly, for example, via the RAN or AN. Typically, the R(AN) comprises base stations, e.g. such as evolved Node Bs (eNBs), or 5G base stations (gNBs), or similar. Seen from the core network side, the 5G core NFs shown ininclude a Network Slice-specific and Stand-alone Non-Public Network (SNPN) Authentication and Authorization Function (NSSAAF), a Network Slice Selection Function (NSSF), an Authentication Server Function (AUSF), a Unified Data Management (UDM), a Network Slice Admission Control Function (NSACF), an Access and Mobility Management Function (AMF), a Session Management Function (SMF), a Policy Control Function (PCF), an Application Function (AF), and a User Plane Function (UPF).

Reference point representations of the 5G network architecture are used to develop detailed call flows in the normative standardization. The N1 reference point is defined to carry signaling between the UE and the AMF. The reference points for connecting between the AN and the AMF, and between the AN and the UPF, are defined as N2 and N3, respectively. There is a reference point, N11, between the AMF and the SMF, which implies that the SMF is at least partly controlled by the AMF. N4 is used by the SMF and the UPF so that the UPF can be set using the control signal generated by the SMF, and the UPF can report its state to the SMF. N9 is the reference point for the connection between different UPFs, and N14 is the reference point connecting between different AMFs, respectively. N15 and N7 are defined since the PCF applies policy to the AMF and the SMF, respectively. N12 is required for the AMF to perform authentication of the UE. N8 and N10 are defined because the subscription data of the UE is required for the AMF and the SMF.

2 FIG. The 5G core network aims at separating user plane and control plane. The user plane carries user traffic while the control plane carries signaling in the network. In, the UPF is in the user plane and all other NFs, i.e., AMF, SMF, PCF, AF, AUSF, and UDM, are in the control plane. Separating the user and control planes guarantees each plane resource to be scaled independently. It also allows UPFs to be deployed separately from control plane functions in a distributed fashion. In this architecture, UPFs may be deployed very close to UEs to shorten the Round Trip Time (RTT) between UEs and data network for some applications requiring low latency.

2 FIG. The core 5G network architecture is composed of modularized functions. For example, the AMF and the SMF are independent functions in the control plane. Separated, the AMF and the SMF allow independent evolution and scaling. Other control plane functions like the PCF and the AUSF can be separated as shown in. Modularized function design enables the 5G core network to support various services flexibly.

Each NF interacts with another NF directly. It is possible to use intermediate functions to route messages from one NF to another NF. In the control plane, a set of interactions between two NFs is defined as service so that its reuse is possible. This service enables support for modularity. The user plane supports interactions such as forwarding operations between different UPFs.

3 FIG. 2 FIG. 2 FIG. 3 FIG. 3 FIG. illustrates a 5G network architecture using service-based interfaces between the NFs in the control plane, instead of the point-to-point reference points/interfaces used in the 5G network architecture as illustrated in. However, the NFs described above with reference tocorrespond to the NFs shown in. The service(s) etc. that an NF provides to other authorized NFs can be exposed to the authorized NFs through the service-based interface(s). Inthe service-based interfaces are indicated by the letter “N” followed by the name of the NF, e.g. Namf for the service-based interface of the AMF, and Nsmf for the service-based interface of the SMF etc.

2 3 FIGS.- Some properties of the NFs shown inmay be described in the following manner. The AMF provides UE-based authentication, authorization, mobility management, etc. A UE using multiple access technologies is basically connected to a single AMF because the AMF is independent of the access technologies. The SMF is responsible for session management and allocates internet protocol (IP) addresses to UEs. It also selects and controls the UPF for data transfer. If a UE has multiple sessions, different SMFs may be allocated to each session to manage them individually and possibly provide different functionalities per session. The AF provides information on the packet flow to the PCF responsible for policy control in order to support Quality of Service (QoS). Based on the information, the PCF determines policies about mobility and session management to make the AMF and the SMF operate properly. The AUSF supports authentication function for UEs, or similar, and thus stores data for authentication of UEs, or similar, while the UDM stores subscription data of the UE. The Data Network (DN), not part of the 5G core network, provides Internet access or operator services and similar.

An NF may be implemented either as a network element on a dedicated hardware, as a software instance running on a generic hardware, or as a virtualized function instantiated on an appropriate platform, e.g., a cloud infrastructure. An SCP can be defined as a node that is configured to operate as an SCP between NF nodes, e.g. the first NF node (e.g. an NF service consumer node) referred to herein and any one or more second NF nodes (e.g. any one or more NF service producer nodes) referred to herein.

If an SCP is deployed, it can be used for indirect communication between NFs and NF services. The SCP does not expose services itself. If indirect communication with delegated discovery (“model D”) is used, the NF service consumer sends the service request to the SCP and provides, within the service request to the SCP, the discovery and selection parameters necessary to discover and select an NF service producer. Thus, in model D, the SCP is operable or configured to perform (or is responsible for performing) NF discovery. The discovery can be referred to as delegated discovery as it can be delegated to the SCP, e.g. by the NF service consumer. For example, in model D, the NF service consumer can send, to the SCP, one or more discovery parameters (or factors) required to find one or more (suitable) NF service producer nodes. The SOP may discover one or more NF service producer nodes (e.g. via an NRF or from its own cache) by using the received one or more discovery parameters.

There is an issue when there are NF service producers deployed with different versions that are non-backward-compatible (NBC) or where there are NFs deployed with NBC versions among them.

Version numbering defines so called minor and major version, e.g. 1.2.0, where 1 is the major version, and 2 is the minor one. A different major version can have NBC changes, but this may happen as well for minor versions.

In NRF discovery, it is possible to include a query parameter “preferred-supported-features”. This query parameter is defined in 3GPP TS 29.510 (see Table 1 below which corresponds to Table 6.2.3.2.3.1-1 of 3GPP TS 29.510).

TABLE 1 URI query parameters supported by a GET method on this resource Name Data type P Cardinality Description Applicability . . . . . . . . . . . . . . . . . . preferred map(string) O 1 . . . N When present, this information Query- -api- element (IE) indicates a preferred Params-Ext2 versions API version of services that are supported by target NF instances. The key of the map is the ServiceName (see clause 6.1.6.3.11 of 3GPP TS 29.510) for which the preferred API version is indicated. Each element carries the API Version Indication for the service indicated by the key. The NRF may return additional NFs in the response not matching the preferred API versions, e.g. if no NF profile is found matching the preferred-api-versions. An API Version Indication is a string formatted as {operator} + {API Version}. The following operators shall be supported: “=” match a version equals to the version value indicated. “>” match any version greater than the version value indicated “>=” match any version greater than or equal to the version value indicated “<““” match any version less than the version value indicated “<=” match any version less than or equal to the version value indicated “{circumflex over ( )}” match any version compatible with the version indicated, i.e. any version with the same major version as the version indicated. Precedence between versions is identified by comparing Major, Minor, and Patch version fields numerically, from left to right. If no operator or an unknown operator is provided in API Version Indication, “=” operator is applied. Example of API Version Indication: Case1: “=1.2.4.operator-ext” or “1.2.4.operator-ext” means matching the service with API version “1.2.4.operator-ext” Case2: “>1.2.4” means matching the service with API versions greater than “1.2.4” Case3: “{circumflex over ( )}2.3.0” or “{circumflex over ( )}2” means matching the service with all API versions with major version “2”.

However, the (discovery) results may include “non-preferred api versions”. If only “preferred -api-versions” are included in the (discovery) results, it can be indicated that the result includes the attribute “preferred Search”, as described in clause 6.2.6.2.2 of 3GPP TS 29.510 (see Table 2 below, which corresponds to Table 6.2.6.2.2-1 of 3GPP TS 29.510).

TABLE 2 Definition of type SearchResult Attribute name Data type P Cardinality Description . . . . . . . . . . . . . . . preferredSearch PreferredSearch C 0 . . . 1 This IE shall be present to indicate whether all the returned NFProfiles match the preferred query parameters, if the discovery request contain any of the query parameter defined in the PreferredSearch data type.

Where PreferredSearch can be as follows (see Table 3 below, which corresponds to Table 6.2.6.2.6-1 of 3GPP TS 29.510):

TABLE 3 Definition of type PreferredSearch Attribute name Data type P Cardinality Description . . . preferredApiVersionsMatchInd boolean O 0 . . . 1 Indicates whether the search result includes at least one NF Profile that matches all the preferred API versions indicated in the query parameter preferred-api-versions. true: Match false: Not Match otherApiVersionsInd boolean O 0 . . . 1 This IE may be present if the preferred- api-versions query parameter is provided in the discovery request. When present, this IE indicates whether there is at least one NF Profile with other API versions, i.e. that does not match all the preferred API versions indicated in the preferred-api- versions, returned in the response or not. true: Returned false: Not returned

Then, even with this information, a client is only able to know whether only preferred-api-versions are included in NF service producer profiles provided, or if other non-preferred API-versions may be included as well. But, it is up to NRF implementation in fact to provide NF service producer profiles with a non-preferred-apiversion.

With this information, if the client is an NF service consumer, unless it is indicated that only NF service producers with preferred-api-versions are provided, the NF service consumer needs to check the api-version in the NF service producer profiles to select the preferred api-version, among the ones provided. Then, the NF service consumer may encode a JavaScript Object Notation (JSON) body in the service request according to the version chosen.

With indirect communication with delegated discovery (model D), the NF service consumer does not perform NRF discovery to get the NF service producer profiles. Instead, this is delegated to the SCP. Some of the following description and figures describe the issues in this case.

There are some variants of existing behaviour, which depend on if a preferred-api-versions query parameter is used and if the NF service producer supports the major versions indicated by the resource URI.

4 FIG. shows an exemplifying signaling diagram illustrating details of a flow where an NF node, (e.g., an NF service consumer) requests a service in model D, in which a preferred-api-versions query parameter is not used.

4 FIG. 4 FIG. 4 FIG. 10 20 30 40 50 60 40 50 60 40 50 60 The example shown ininvolves an NFc1, which is an NF service consumer, an NRF, an SCP, and NF service producers,,(i.e. NFp1, NFp2, and NFp3). In the example illustrated in, NFp1provides v1.2.0 of the service, NFp2provides v1.3.0 of the service, and NFp3provides v2.0.0 of the service.is only an example, and it is known that the number of the NF service producers and the services provided by the NF service producers are shown only for illustration, and that other numbers of NF service producers and/or services is possible.

10 30 30 401 30 10 4 FIG. 4 FIG. 4 FIG. When a service consumer entity, for example NFc1, requests the SCPfor a service, it may transmit a service request (i.e. a request for a service), e.g. “Nnfp_serv_v2_req”, to the SCPin step Sof. Thus, the SCPcan receive the service request from the NFc1. The API-version is included in the ResourceURI as standardized, e.g. v2 in the example illustrated in. In the example illustrated in, sbi-discovery-* does not include sbi-discovery-preferred-apiversions.

402 30 20 20 30 4 FIG. In step Sof, the SCPmay transmit a discovery request, e.g. “Nnrf_NFDisc req”, to the NRF, to find the corresponding NF service producer profiles. Thus, the NRFcan receive the discovery request from the SCP.

403 20 40 50 60 40 50 60 30 40 50 60 20 4 FIG. In step Sof, the NRFcan provide all available NF service producer instances,,, i.e., NFp1, NFp2and NFp3. Thus, the SCPcan receive all available NF service producer instances,,(NRF discovered results) from the NRF.

404 30 40 30 40 4 FIG. In step Sof, the SCPmay select one NF service producerfrom NRF discovered results. The SCPmay select an NF service producer that does not support the required version, e.g. NFp1in the example.

405 30 40 40 40 30 4 FIG. In step Sof, the SCPmay transmit the service request to the selected NF service producer, i.e., NFp1. Thus, NFp1can receive the service request from the SCP.

4 FIG. 4 FIG. 40 406 30 40 In the example illustrated in, NFp1is unable to process the request, since this version of the API is not supported. Accordingly, in step Sof, the SCPcan receive a response from NFp1, including an error.

30 30 30 407 4 FIG. The SCPis unable to solve the situation, since the resource URI is constructed based on API-version v2. The SCPcannot modify the resource URI. So, the SCPmay forward the error response to the NFc1 in step Sof.

10 30 10 10 30 4 FIG. NFc1can thus receive the error response from the SCP, but has no knowledge of the information to retry. Accordingly, NFc1is unable to retry or to react upon this error by any means. In the example illustrated in, since the NF service consumer (i.e. NFc1) in model D does not perform NRF discovery, the request sent to the SCPfails.

5 FIG. shows an exemplifying signaling diagram illustrating details of a flow where an NF node, (e.g., an NF service consumer) requests a service in model D, in which preferred-api-versions query parameter is used and there is an available NF service producer supporting the major versions indicated by the resource URI.

5 FIG. 5 FIG. 5 FIG. 10 20 30 40 50 60 40 50 60 40 50 60 The example shown ininvolves an NFc1, which is an NF service consumer, an NRF, an SCP, and NF service producers,,(i.e. NFp1, NFp2, and NFp3). In the example illustrated in, NFp1provides v1.2.0 of the service, NFp2provides v1.3.0 of the service, and NFp3provides v2.0.0 of the service.is only an example, and it is known that the number of the NF service producers and the services provided by the NF service producers are shown only for illustration, and that other numbers of NF service producers and/or services is possible.

10 30 30 501 30 10 5 FIG. 5 FIG. 5 FIG. When a service consumer entity, for example NFc1, requests the SCPfor a service, it may transmit a service request (i.e. a request for a service), e.g. “Nnfp_serv_v2_req”, to the SCPin step Sof. Thus, the SCPcan receive the service request from the NFc1. The API-version is included in the ResourceURI as standardized, e.g. v2 in the example illustrated in. In the example illustrated in, sbi-discovery-* includes an sbi-discovery-preferred-apiversions header, e.g. {circumflex over ( )}2, which means matching the service with all API versions with major version “2”.

502 30 20 20 30 5 FIG. In step Sof, the SCPmay transmit a discovery request, e.g. “Nnrf_NFDisc req”, to the NRF, to find the corresponding NF service producer profiles. Thus, the NRFcan receive the discovery request from the SCP. The “sbi-discovery-preferred-apiversions” header can be included in the discovery request as a query parameter for the NRF discovery.

503 20 30 30 20 20 5 FIG. In step Sof, the NRFmay provide a discovery response to the SCP. Thus, the SCPcan receive the discovery response from the NRF. For example, the NRFmay provide only an exact match for API-version with major version “2”, or include other profiles as well. This is unknown.

504 30 5 FIG. 30 30 40 405 408 4 FIG. 4 FIG. Variant a): Assume other non-preferred-apiversion profiles are included as well as discovery results, and this is indicated to the SCP. Then, the SCPmay choose any random profile from the results, e.g. NFp1, the same flow as in. In this case, steps Sto Sofmay be reproduced. 20 60 20 30 60 Variant b): Only exact match results are provided from the NRF. In this case, only NFp3is provided from the NRF(since NFp3 supports the required version (i.e. major version “2”)). The SCPmay then select NFp3. In step Sof, the SCPmay select one NF service producer from NRF discovered results. There may be different possible variants of behaviour depending on the NRF and SCP behaviour, for example:

505 30 60 60 30 5 FIG. In step Sof, the SCPcan transmit the service request to the selected NF service producer, i.e., NFp3. Thus, the NFp3can receive the service request from the SCP.

5 FIG. 5 FIG. 60 506 30 60 In the example illustrated in, NFp3is able to process the request. Accordingly, in step Sof, the SCPcan receive a service response from NFp3, indicating successful processing of the service request.

30 10 507 10 30 5 FIG. The SCPcan forward the successful service response to the NFc1, in step Sof. Thus, the NFc1can receive the successful service response from the SCP.

6 FIG. 700 700 illustratively shows a flowchart of a methodfor requesting a service with an SCP in model D, according to an exemplary embodiment of the present disclosure. In an embodiment, the methodmay be performed at a first Network Function (NF) node. The first NF node may be, for example, an NF service consumer.

6 FIG. 700 710 730 As shown in, the methodmay include steps Sto S.

710 6 FIG. In step Sof, the first NF node transmits a request for the service to the SCP. The request comprises at least an indication indicating a required API version for the service (e.g. an API version for the service that is required to the first NF node). The indication (or the required API version indicated by the indication) is other than an API version included in a Resource URI in the request.

Herein, the expression “a required API version for the service” (or, for example, the expression “an API version required to the first NF node”) can mean that the API version is required to be able to (e.g. receive and) process the service request that is transmitted by the first NF node. An NF node having the API version can process the service request encoded by the first NF node.

The SCP can then search for a second NF node that provides the service of the required API version, and can transmit the service request to the second NF node to process the service request. In response, the SCP can receive a response from the second NF node. The response from the second NF node can be transmitted from the SCP to the first NF node. Thus, the first NF node can receive the response from the SCP. In some cases, there may be no such second NF node that provides the service of the required API version.

700 720 720 6 FIG. In an exemplary embodiment of the present disclosure, the methodmay further comprise step S. In step Sof, the first NF node may receive, from the SCP, a response including an error message indicating that no second NF node provides the required API version for the service.

In an exemplary embodiment of the present disclosure, if there is no second NF node that provides the service of the required API version, the SCP may search for another second NF node that provides the service but has an API version different from the required API version. If there is such a second NF node that provides the service of a different API version, the SCP may provide information on the different API version to the first NF node. Therefore, in some embodiments, the response from the SCP can further include information on an API version for the service of at least one second NF node that provides an API version different from the required API version for the service.

700 730 730 6 FIG. In an exemplary embodiment of the present disclosure, the methodmay further comprise step S. In step Sof, the first NF node may construct a different request for the service by changing the required API version. The first NF node, when it receives a response including an error message indicating that no second NF node provides the required API version for the service, can retry a service request by changing the API version.

In an exemplary embodiment of the present disclosure, the first NF node may construct a different request for the service by taking the received information on the different API version into account. If the first NF node supports the different API version informed by the SCP, it may construct a different service request using the different API version.

In an exemplary embodiment of the present disclosure, the required API version may only indicate a major version. In these embodiments, only the “major version” may be taken as the required API version.

7 FIG. 800 800 illustratively shows a flowchart of a methodfor processing a service request according to an exemplary embodiment of the present disclosure. In an embodiment, the methodmay be performed at an SCP.

7 FIG. 800 810 860 As shown in, the methodmay include steps Sto S.

810 7 FIG. In step Sof, the SCP receives a request for a service from a first NF node. The request includes an indication indicating a required API version for the service (e.g. an API version for the service that is required to the first NF node). The indication (or the required API version indicated by the indication) is other than an API version included in a resource URI in the request.

810 810 7 FIG. 7 FIG. In another example, in step S′ of, the SCP may receive a request for a service from a first NF node, where no such indication is included in the request. In step S′ of, the SCP may extract an API version from a Resource URI in the request, as a required API version for the first NF node.

820 7 FIG. In step Sof, the SCP searches for a second NF node that provides the service of the required API version.

In an exemplary embodiment of the present disclosure, the SCP may transmit, to an NRF, an NF discovery request for discovering a second NF node that provides the service of the required API version. Thus, the NRF can receive the NF discovery request from the SCP.

In an exemplary embodiment of the present disclosure, the SCP may search in its cache (or memory) for the second NF node that provides the service of the required API version.

800 830 830 7 FIG. In an exemplary embodiment of the present disclosure, there may be no such second NF node that provides the service of the required API version. In this case, the methodmay further comprise step S. In step Sof, the SCP may transmit a response to the first NF node, including an error message indicating that no second NF node provides the required API version for the service. Thus, the first NF node can receive the response from the SCP.

800 840 840 800 850 850 800 860 860 7 FIG. 7 FIG. 7 FIG. In an exemplary embodiment of the present disclosure, if there is no such second NF node that provides the service of the required API version, the methodmay further comprise step S. In step Sof, the SCP may search for at least one second NF node that provides the service of an API version different from the required API version. If such a second NF node is found, the methodmay further comprise step S. In step Sof, the SCP may include information on the different API version for the service of the at least one second NF node, if any, in the response to the first NF node. The methodmay further comprise step S. In step Sof, the SCP may extract the information on the different API version from a profile of the at least one second NF node. If the first NF node supports the different API version informed by the SCP, the first NF node may construct a different service request using the different API version.

In an exemplary embodiment of the present disclosure, the required API version may only indicate a major version. In these embodiments, only the “major version” may be taken as the required API version.

8 FIG. 6 7 FIGS.and shows an exemplifying signaling diagram illustrating details of the methods schematically illustrated in.

8 FIG. 8 FIG. 8 FIG. 10 20 30 40 50 60 70 40 50 60 70 40 50 60 70 The example shown ininvolves an NFc1, which is an NF service consumer, an NRF, an SCP, and NF service producers,,,(i.e. NFp1, NFp2, NFp3, and NFp4). In the example illustrated in, NFp1provides v1.2.0 of the service, NFp2provides v1.3.0 of the service, NFp3provides v2.1.0 of the service, and NFp4provides v2.0.0 of the service.is only an example, and it is known that the number of the NF service producers and the services provided by the NF service producers are shown only for illustration, and that other numbers of NF service producers and/or services is possible.

910 10 30 30 10 30 910 710 810 8 FIG. 8 FIG. 8 FIG. 6 FIG. 7 FIG. In step Sof, the NFc1transmits a service request to the SCP. Thus, the SCPcan receive the service request from the NFc1. In some embodiments, a new sbi-discovery-required-apiversion header can be included in the service request. This header can include the API-version(s) required for the NF service producer to be able to successfully process an encoded JSON body of the request. That is, the API-version can include all the BC (backward compatible) versions with the one (version) that is selected for encoding the request. Therefore, the SCPcan be provided with information of required API-version(s). For the purposes of the example illustrated in, the service request can be considered to be encoded with version 2.1.0, and this version is BC with v2.0.0. This encoding is not BC with version 1.x.y (i.e. any version where 1 is the major). Step Sofis an example of step Sshown inand step Sshown in.

920 30 20 30 30 920 30 30 920 820 8 FIG. 8 FIG. 8 FIG. 7 FIG. In step Sof, the SCPmay transmit a discovery request towards the NRF. Thus, the NRF can receive the discovery request from the SCP. The SCPcan perform an NRF Discovery using the (new) information (of API-version(s)) as input. In step Sof, the (new) information can be comprised in the discovery request. As an alternative, NRF results may be cached (e.g. stored) in the SCP, and the SCPmay search in its cache (or memory) using the (new) information (of API-version(s)) as an input. Step Sofis an example of step Sshown in.

930 20 30 30 20 60 70 940 30 60 8 FIG. 8 FIG. 8 FIG. In step Sof, the NRFmay provide corresponding profiles (e.g. to the SCP, in response to the discovery request). Thus, the SCPcan receive the corresponding profiles from the NRF. In the example illustrated in, the corresponding profiles can be those associated with NFp3and NFp4. In step Sof, the SCPmay select one NF service producer, e.g. NFp3. In any case, all the provided NF service producers support the service request.

950 30 60 60 30 8 FIG. In step Sof, the SCPmay transmit the service request to the selected NF service producer, i.e., NFp3. Thus, the selected NF service producer, i.e. NFp3, can receive the service request from the SCP.

8 FIG. 8 FIG. 60 960 30 60 In the example illustrated in, NFp3is able to process the request. Accordingly, in step Sof, the SCPmay receive a service response from NFp3, indicating successful processing of the service request.

970 30 10 10 30 8 FIG. In step Sof, the SCPmay forward the successful service response to the NFc1. Thus, the NFc1can receive the successful service response from the SCP.

9 FIG. 6 7 FIGS.and shows another exemplifying signaling diagram illustrating details of the methods schematically illustrated in.

9 FIG. 8 FIG. 9 FIG. 10 20 30 40 50 60 70 40 50 60 70 40 50 60 70 The example shown ininvolves an NFc1, which is an NF service consumer, an NRF, an SCP, and NF service producers,,,(i.e. NFp1, NFp2, NFp3, and NFp4). In the example illustrated in, NFp1provides v1.2.0 of the service, NFp2provides v1.3.0 of the service, NFp3provides v2.1.0 of the service, and NFp4provides v2.0.0 of the service.is only an example, and it is known that the number of the NF service producers and the services provided by the NF service producers are shown only for illustration, and that other numbers of NF service producers and/or services is possible.

1010 10 30 30 10 9 FIG. In step Sof, the NFc1transmits a service request to the SCP. Thus, the SCPcan receive the service request from the NFc1. In some embodiments, the request may not include any new information, nor a preferred-api-version header.

1020 30 1020 810 9 FIG. 9 FIG. 9 FIG. 7 FIG. In step Sof, the SCPmay extract an api version from a Resource URI. As illustrated in the example of, in some embodiments, this version can be “v2”. Step Sofis an example of step S′ shown in.

1030 1080 920 970 9 FIG. 8 FIG. Steps Sto Sofcan be described by reference to the steps Sto Sof, and therefore detailed explanation is omitted here for simplicity.

10 FIG. 6 7 FIGS.and shows still another exemplifying signaling diagram illustrating details of the methods schematically illustrated in.

10 FIG. 10 FIG. 10 FIG. 10 20 30 40 50 40 50 40 50 The example shown ininvolves an NFc1, which is an NF service consumer, an NRF, an SCP, and NF service producers,(i.e. NFp1and NFp2). In the example illustrated in, NFp1provides v1.2.0 of the service, and NFp2provides v1.3.0 of the service.is only an example, and it is known that the number of the NF service producers and the services provided by the NF service producers are shown only for illustration, and that other numbers of NF service producers and/or services is possible.

1110 10 30 30 10 30 1110 710 810 10 FIG. 10 FIG. 10 FIG. 6 FIG. 7 FIG. In step Sof, the NFc1transmits a service request to the SCP. Thus, the SCPcan receive the service request from the NFc1. In some embodiments, a new sbi-discovery-required-apiversion header can be included in the service request. In some embodiments, this header can include an API-version(s) required for the NF service producer to be able to successfully process an encoded JSON body of the request. That is, the API-version may include all BC (backward compatible) versions that are BC with the one (version) that is selected for encoding the request. Therefore, the SCPcan be provided with information of required API-version(s). For the purpose of the example illustrated in, the service request can be encoded with version 2.1.0. Version 2.1.0 can, for example, be BC with v2.0.0. Version 2.1.0 may not, for example, be BC with version 1.x.y. Step Sofis an example of step Sshown inand step Sshown in.

1120 30 20 20 30 30 30 30 1120 820 10 FIG. 10 FIG. 7 FIG. In step Sof, the SCPmay transmit a discovery request towards the NRF. Thus, the NRFcan receive the discovery request from the SCP. The SCPcan perform an NRF Discovery using the (new) information as input. The information can be comprised in the discovery request. As an alternative, the NRF results may be cached (or stored) in the SCP, and the SCPmay search in its cache (or memory) using the (new) information as an input. Step Sofis an example of step Sshown in.

10 FIG. 10 FIG. 1130 20 30 30 20 As shown in the example illustrated in, in some embodiments, no NF service producer that provides version 2 of the service may be found. In step Sof, the NRFmay transmit, towards the SCP, a discovery response indicating that no NF profile is found. Thus, the SCPcan receive the discovery response from the NRF.

1140 30 1140 840 10 FIG. 10 FIG. 7 FIG. In step Sof, in some embodiments, the SCPmay resend the NF discovery request without the new “required-apiversion” query. Step Sofis an example of step Sshown in.

10 FIG. 10 FIG. 10 FIG. 40 50 1150 20 40 50 30 40 50 20 As shown in the example illustrated in, in some embodiments, some profiles can be found. In the example illustrated by, NFp1and NFp2may be qualified (e.g. assuming that they fulfil all the other discovery parameters). In step Softhe NRFmay provide the profiles of NFp1and NFp2. Thus, the SCPcan receive the profiles of NFp1and NFp2from the NRF.

1160 30 1160 860 10 FIG. 10 FIG. 7 FIG. In step Sof, the SCPmay extract the api-versions from the provided NF service producer profiles (e.g. that are functionally valid but does not fulfil the required-apiversion). Step Sofis an example of step Sshown in.

10 FIG. 10 FIG. 1170 30 10 10 30 30 10 In the example illustrated in, a new error response can be defined, to indicate there is no valid result for the “required-apiversions”. As extra information, the error response may include any other api-version that fulfils functional requirements, but not the “required-version”. In step Sof, the SCPmay transmit a response to the NFc1. Thus, the NFc1can receive the response from the SCP. The response transmitted by the SCPto the NFc1can include information on v1.

1180 10 10 10 FIG. In step Sof, based on the error received, the NFc1can know there is no valid result for the “required-apiversions”, and also that there are available versions. If the available versions are supported, the NFc1is able to adapt the encoded service request on available versions, i.e., from v2 to v1.

1190 910 10 10 FIG. 8 FIG. 8 FIG. 10 FIG. Step Sofis similar to step Sin, where the NFc1may transmit a service request with v1 as the required API version in the sbi-discovery-required-apiversion header. The subsequent steps illustrated incan also apply to the method illustrated in, that is, the request can be successfully executed.

11 FIG. 11 FIG. 8 10 FIGS.to 11 FIG. 6 FIG. 1200 10 1200 700 1200 700 Hereinafter, a structure of a first NF node will be described with reference to.illustratively shows a schematic structure diagram of a first NF node(e.g. NFc1as shown in, as described previously) according to an exemplary embodiment of the present disclosure. The first NF nodeinmay perform the methodfor requesting a service described previously with reference to. Accordingly, some detailed description on the first NF nodemay refer to the corresponding description of the methodfor requesting a service as previously discussed.

11 FIG. 11 FIG. 1200 1202 1204 1206 1200 1202 1204 As shown in, the first NF nodemay include a receiving module, a transmitting module, and a processing module. As will be understood by the person skilled in the art, common components in the first NF nodeare omitted infor not obscuring the idea of the present disclosure. Also, some modules may be distributed in more modules or integrated into fewer modules. For example, the receiving moduleand the transmitting modulemay be integrated into a transceiver module.

1204 1200 In an exemplary embodiment of the present disclosure, the transmitting moduleof the first NF nodemay be configured to transmit a request for the service to an SCP. The request comprises at least an indication indicating a required API version for the service (e.g. an API version for the service that is required to the first NF node). The indication (or the required API version indicated by the indication) is other than an API version included in a Resource URI in the request.

The SCP may then search for a second NF node that provides the service of the required API version. The SCP may transmit the service request to the second NF node to process the service request, and in response may receive a response from the second NF node, which response may be transmitted to the first NF node. In some cases, there may be no such second NF node that provides the service of the required API version.

1202 1200 In an exemplary embodiment of the present disclosure, the receiving moduleof the first NF nodemay be configured to receive, from the SCP, a response including an error message indicating that no second NF node provides the required API version for the service.

In an exemplary embodiment of the present disclosure, if there is no second NF node that provides the service of the required API version, the SCP may search for another second NF node that provides the service but has an API version different from the required API version. If there is such a second NF node that provides the service of a different API version, the SCP may provide information on the different API version to the first NF node. In this example, the response from the SCP can further include information on an API version for the service of at least one second NF node that provides an API version different from the required API version for the service.

1206 1200 1200 In an exemplary embodiment of the present disclosure, the processing moduleof the first NF nodemay be configured to construct a different request for the service by changing the required API version. The first NF node, after receiving a response including an error message indicating that no second NF node provides the required API version for the service, can retry a service request by changing the API version.

1206 1200 1200 1206 1200 In an exemplary embodiment of the present disclosure, the processing moduleof the first NF nodemay be configured to construct a different request for the service by taking the received information on the different API version into account. If the first NF nodesupports the different API version informed by the SCP, the processing moduleof the first NF nodemay be configured to construct a different service request using the different API version.

1300 1300 10 1300 700 1300 700 12 FIG. 12 FIG. 8 10 FIGS.to 12 FIG. 6 FIG. Hereinafter, another structure of a first NF nodewill be described with reference to.illustratively shows a schematic structure diagram of a first NF node(e.g., NFc1as shown in, as described previously) according to an exemplary embodiment of the present disclosure. The first NF nodeinmay perform the methodfor requesting a service described previously with reference to. Accordingly, some detailed description on the first NF nodemay refer to the corresponding description of the methodfor requesting a service as previously discussed.

12 FIG. 1300 1303 1305 1305 1300 1301 As shown in, the first NF nodemay include at least one controller or processorincluding, e.g. any suitable Central Processing Unit (CPU), microcontroller, Digital Signal Processor (DSP), etc., capable of executing computer program instructions. The computer program instructions may be stored in a memory. The memorymay be any combination of a Random Access Memory (RAM) and a Read Only Memory (ROM). The memory may also comprise persistent storage which, for example, can be any single one or combination of magnetic memory, optical memory, or solid state memory or even remotely mounted memory. The exemplary first NF nodefurther comprises a communication interfacearranged for communication.

1305 1303 1300 700 The instructions, when loaded from the memoryand executed by the at least one processor, may cause the first NF nodeto perform the methodfor requesting a service as previously discussed.

1305 1303 1300 In particular, in an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the first NF nodeto transmit a request for the service to an SCP. The request comprises at least an indication indicating a required API version for the service (e.g. an Application Program Interface, API, version for the service that is required to the first NF node). The indication (or the required API version indicated by the indication) is other than an API version included in a Resource URI in the request.

The SCP can then search for a second NF node that provides the service of the required API version. The SCP may transmit the service request to the second NF node to process the service request, and in response can receive a response from the second NF node, which response may be transmitted to the first NF node. In some cases, there may be no such second NF node that provides the service of the required API version.

1305 1303 1300 in an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the first NF nodeto receive from the SCP a response including an error message indicating that no second NF node provides the required API version for the service.

In an exemplary embodiment of the present disclosure, if there is no second NF node that provides the service of the required API version, the SCP may search for another second NF node that provides the service but has an API version different from the required API version. If there is such a second NF node that provides the service of a different API version, the SCP may provide information on the different API version to the first NF node. In this example, the response from the SCP can further include information on an API version for the service of at least one second NF node that provides an API version different from the required API version for the service.

1305 1303 1300 1300 In an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the first NF nodeto construct a different request for the service by changing the required API version. The first NF node, after receiving a response including an error message indicating that no second NF node provides the required API version for the service, can retry a service request by changing the API version.

1305 1303 1300 1300 1300 In an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the first NF nodeto construct a different request for the service by taking the received information on the different API version into account. If the first NF nodesupports the different API version informed by the SCP, the first NF nodemay be configured to construct a different service request using the different API version.

13 FIG. 13 FIG. 8 10 FIGS.to 13 FIG. 7 FIG. 1400 1400 800 1400 800 Hereinafter, a structure of an SCP will be described with reference to.illustratively shows a schematic structure diagram of an SCP(e.g. SCP as shown in, as described previously) according to an exemplary embodiment of the present disclosure. The SCPinmay perform the methodfor processing a service request described previously with reference to. Accordingly, some detailed description on the SCPmay refer to the corresponding description of the methodfor processing a service request as previously discussed.

13 FIG. 13 FIG. 1400 1402 1404 1406 1408 1400 1402 1406 As shown in, the SCPmay include a receiving module, a searching module, a transmitting module, and an extracting module. As will be understood by the person skilled in the art, common components in the SCPare omitted infor not obscuring the idea of the present disclosure. Also, some modules may be distributed in more modules or integrated into fewer modules. For example, the receiving moduleand the transmitting modulemay be integrated into a transceiver module.

1402 1400 In an exemplary embodiment of the present disclosure, the receiving moduleof the SCPmay be configured to receive a request for a service from a first NF node, the request including an indication indicating a required API version for the service (e.g. an API version for the service that is required to the first NF node). The indication (or the required API version indicated by the indication) is other than an API version included in a resource URI in the request.

1402 1400 1408 1400 In another example, the receiving moduleof the SCPmay be configured to receive a request for a service from a first NF node, where no such indication is included in the request. The extracting moduleof the SCPmay be configured to extract an API version from a Resource URI in the request, as a required API version for the first NF node.

1404 1400 In an exemplary embodiment of the present disclosure, the searching moduleof the SCPmay be configured to search for a second NF node that provides the service of the required API version.

1404 1400 1406 In an exemplary embodiment of the present disclosure, the searching moduleof the SCPmay be configured to transmit (e.g. by means of the transmitting module), to an NRF, an NF discovery request for discovering a second NF node that provides the service of the required API version.

1404 1400 In an exemplary embodiment of the present disclosure, the searching moduleof the SCPmay be configured to search in its cache for the second NF node that provides the service of the required API version.

1406 1400 In an exemplary embodiment of the present disclosure, there may be no such second NF node that provides the service of the required API version. In this case, the transmitting moduleof the SCPmay be configured to transmit a response to the first NF node, including an error message indicating that no second NF node provides the required API version for the service.

1404 1400 1406 1400 1408 1400 In an exemplary embodiment of the present disclosure, if there is no such second NF node that provides the service of the required API version, the searching moduleof the SCPmay be configured to search for at least one second NF node that provides the service of an API version different from the required API version. If such an at least one second NF node is found, the transmitting moduleof the SCPmay be configured to transmit the response to the first NF node which includes information on the different API version for the service of the at least one second NF node. In particular, the extracting moduleof the SCPmay be configured to extract the information on the different API version from a profile of the at least one second NF node. If the first NF node supports the different API version informed by the SCP, it may construct a different service request using the different API version.

14 FIG. 14 FIG. 8 10 FIGS.to 14 FIG. 7 FIG. 1500 1500 800 1500 800 Hereinafter, another structure of an SCP will be described with reference to.illustratively shows a schematic structure diagram of a second NF node SCP(e.g., SCP as shown in, as described previously) according to an exemplary embodiment of the present disclosure. The SCPinmay perform the methodfor processing a service request described previously with reference to. Accordingly, some detailed description on the SCPmay refer to the corresponding description of the methodfor processing a service request as previously discussed.

14 FIG. 1500 1503 1505 1505 1500 1501 As shown in, the SCPmay include at least one controller or processorincluding, e.g. any suitable Central Processing Unit (CPU) microcontroller, Digital Signal Processor (DSP) etc., capable of executing computer program instructions. The computer program instructions may be stored in a memory. The memorymay be any combination of a RAM and a ROM. The memory may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, or solid state memory or even remotely mounted memory. The exemplary SCPfurther comprises a communication interfacearranged for communication.

1505 1503 1500 800 7 FIG. The instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto perform the methodfor processing a service request described previously with reference to.

1505 1503 1500 In particular, in an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto receive a request for a service from a first NF node, the request including an indication indicating a required API version for the service (e.g. an API version for the service that is required to the first NF node). The indication (or the required API version indicated by the indication) is other than an API version included in a resource URI in the request.

1505 1503 1500 1505 1503 1500 In another example, in an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto receive a request for a service from a first NF node, where no such indication is included in the request. The instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto extract an API version from a Resource URI in the request, as a required API version for the first NF node.

1505 1503 1500 In an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto search for a second NF node that provides the service of the required API version.

1505 1503 1500 In an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto transmit, to an NRF, an NF discovery request for discovering a second NF node that provides the service of the required API version.

1505 1503 1500 In an exemplary embodiment of the present disclosure, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto search in its cache for the second NF node that provides the service of the required API version.

1505 1503 1500 In an exemplary embodiment of the present disclosure, there may be no such second NF node that provides the service of the required API version. In the case, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto transmit a response to the first NF node, including an error message indicating that no second NF node provides the required API version for the service.

1505 1503 1500 1505 1503 1500 1505 1503 1500 In an exemplary embodiment of the present disclosure, if there is no such second NF node that provides the service of the required API version, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto search for at least one second NF node that provides the service of an API version different from the required API version. If such an at least one second NF node is found, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto transmit the response to the first NF node which includes information on the different API version for the service of the at least one second NF node. In particular, the instructions, when loaded from the memoryand executed by the at least one processor, may cause the SCPto extract the information on the different API version from a profile of the at least one second NF node. If the first NF node supports the different API version informed by the SCP, it may construct a different service request using the different API version.

Other embodiments of the present disclosure are defined in the following numbered statements:

700 710 transmitting (S) a request for the service to the SCP, the request comprising at least an indication indicating an Application Program Interface, API, version for the service that is required to the first NF node, wherein the indication is other than an API version included in a Resource Uniform Resource Identifier, URI, in the request. Statement 1. A method () at a first Network Function, NF, node for requesting a service with a Service Communication Proxy, SCP, in model D, comprising:

720 receiving (S) from the SCP a response including an error message indicating that no second NF node provides the required API version for the service. Statement 2. The method of Statement 1, further comprising:

Statement 3. The method of Statement 2, wherein the response further includes information on an API version for the service of at least one second NF node that provides an API version different from the required API version for the service.

730 constructing (S) a different request for the service by changing the required API version. Statement 4. The method of Statement 3, further comprising:

Statement 5. The method of Statement 4, wherein constructing a different request for the service is performed by taking the received information on the different API version into account.

Statement 6. The method of any of Statements 1 to 3, wherein the required API version only indicates a major version.

800 810 receiving (S) a request for a service from a first Network Function, NF, node, the request including an indication indicating an Application Program Interface, API, version for the service that is required to the first NF node, wherein the indication is other than an API version included in a Resource Uniform Resource Identifier, URI, in the request; and 820 searching (S) for a second NF node that provides the service of the required API version. Statement 7. A method () at a Service Communication Proxy, SCP, in model D, comprising:

transmitting, to a Network Function Repository Function, NRF, a NF discovery request for discovering a second NF node that provides the service of the required API version; or searching in its cache for the second NF node. Statement 8. The method of Statement 7, wherein searching for a second NF node comprises:

830 transmitting (S) a response to the first NF node, including an error message indicating that no second NF node provides the required API version for the service. Statement 9. The method of Statement 7 or 8, further comprising:

840 searching (S) for at least one second NF node that provides the service of an API version different from the required API version. Statement 10. The method of Statement 9, further comprising:

850 including (S) information on the different API version for the service of the at least one second NF node, if any, in the response to the first NF node. Statement 11. The method of Statement 10, further comprising:

860 extracting (S) the information on the different API version from a profile of the at least one second NF node. Statement 12. The method of Statement 11, further comprising:

Statement 13. The method of any of Statements 7 to 12, wherein the required API version only indicates a major version.

800 810 receiving (S′) a request for a service from a first Network Function, NF, node; 810 extracting (S′) an API version from a Resource Uniform Resource Identifier, URI, in the request, as a required API version for the first NF node; and 820 searching (S) for a second NF node that provides the service of the required API version. Statement 14. A method () at a Service Communication Proxy, SCP, in model D, comprising:

transmitting, to a Network Function Repository Function, NRF, a NF discovery request for discovering a second NF node that provides the service of the required API version; or searching in its cache for the second NF node. Statement 15. The method of Statement 14, wherein searching for a second NF node comprises:

830 transmitting (S) a response to the first NF node, including an error message indicating that no second NF node provides the required API version for the service. Statement 16. The method of Statement 14 or 15, further comprising:

840 searching (S) for at least one second NF node that provides the service of an API version different from the required API version. Statement 17. The method of Statement 16, further comprising:

850 including (S) information on the different API version for the service of the at least one second NF node, if any, in the response to the first NF node. Statement 18. The method of Statement 17, further comprising:

860 extracting (S) the information on the different API version from a profile of the at least one second NF node. Statement 19. The method of Statement 18, further comprising:

1300 1301 a communication interface () arranged for communication, 1303 at least one processor (), and 1305 1300 transmit a request for the service to the SCP, the request comprising at least an indication indicating an Application Program Interface, API, version for the service that is required to the first NF node, wherein the indication is other than an API version included in a Resource Uniform Resource Identifier, URI, in the request. a memory () comprising instructions which, when executed by the at least one processor, cause the first NF node () to: Statement 20. A first Network Function, NF, node () for requesting a service with a Service Communication Proxy, SCP, in model D, comprising:

1300 receive from the SCP a response including an error message indicating that no second NF node provides the required API version for the service. Statement 21. The first NF node () of Statement 20, wherein the instructions which, when executed by the at least one processor, further cause the first NF node to:

1300 Statement 22. The first NF node () of Statement 21, wherein the response further includes information on an API version for the service of at least one second NF node that provides an API version different from the required API version for the service.

1300 construct a different request for the service by changing the required API version. Statement 23. The first NF node () of Statement 22, wherein the instructions which, when executed by the at least one processor, further cause the first NF node to:

1300 construct a different request for the service by taking the received information on the different API version into account. Statement 24. The first NF node () of Statement 23, wherein the instructions which, when executed by the at least one processor, further cause the first NF node to:

1300 Statement 25. The first NF node () of any of Statements 20 to 22, wherein the required API version only indicates a major version.

1500 1501 a communication interface () arranged for communication, 1503 at least one processor (), and 1505 1500 receive a request for a service from a first Network Function, NF, node, the request including an indication indicating an Application Program Interface, API, version for the service that is required to the first NF node, wherein the indication is other than an API version included in a Resource Uniform Resource Identifier, URI, in the request; and search for a second NF node that provides the service of the required API version. a memory () comprising instructions which, when executed by the at least one processor, cause the SCP () to: Statement 26. A Service Communication Proxy, SCP () in model D, comprising:

1500 transmit, to a Network Function Repository Function, NRF, a NF discovery request for discovering a second NF node that provides the service of the required API version; or search in its cache for the second NF node. Statement 27. The SCP () of Statement 26, wherein the instructions which, when executed by the at least one processor, further cause the SCP to:

1500 transmit a response to the first NF node, including an error message indicating that no second NF node provides the required API version for the service. Statement 28. The SCP () of Statement 26 or 27, wherein the instructions which, when executed by the at least one processor, further cause the SCP to:

1500 search for at least one second NF node that provides the service of an API version different from the required API version. Statement 29. The SCP () of Statement 28, wherein the instructions which, when executed by the at least one processor, further cause the SCP to:

1500 include information on the different API version for the service of the at least one second NF node, if any, in the response to the first NF node. Statement 30. The SCP () of Statement 29, wherein the instructions which, when executed by the at least one processor, further cause the SCP to:

1500 Statement 31. The SCP () of any of Statements 26 to 30, wherein the required API version only indicates a major version.

1500 a communication interface arranged for communication, at least one processor, and receive a request for a service from a first Network Function, NF, node; extract an API version from a Resource Uniform Resource Identifier, URI, in the request, as a required API version for the first NF node; and search for a second NF node that provides the service of the required API version. a memory comprising instructions which, when executed by the at least one processor, cause the SCP to: Statement 32. A Service Communication Proxy, SCP (), in model D, comprising:

Statement 33. A computer readable storage medium having computer program instructions stored thereon, the computer program instructions, when executed by a processor in a network device, causing the network device to perform the method according to any of Statements 1-19.

The foregoing description of implementations provides illustration and description, but is not intended to be exhaustive or to limit the disclosure to the precise form disclosed. Modifications and variations are possible in light of the above teachings, or may be acquired from practice of the disclosure.

Aspects of the disclosure may also be embodied as methods and/or computer program products. Accordingly, the disclosure may be embodied in hardware and/or in software (including firmware, resident software, microcode, etc.). Furthermore, the embodiments may take the form of a computer program product on a computer-usable or computer-readable storage medium having computer-usable or computer-readable program code embodied in the medium for use by or in connection with an instruction execution system. Such instruction execution system may be implemented in a standalone or distributed manner. The actual software code or specialized control hardware used to implement embodiments described herein is not limiting of the disclosure. Thus, the operation and behavior of the aspects were described without reference to the specific software code, it being understood that those skilled in the art will be able to design software and control hardware to implement the aspects based on the description herein.

Furthermore, certain portions of the disclosure may be implemented as “logic” that performs one or more functions. This logic may include hardware, such as an application specific integrated circuit or field programmable gate array or a combination of hardware and software.

It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps, components or groups but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

No element, act, or instruction used in the disclosure should be construed as critical or essential to the disclosure unless explicitly described as such. Also, as used herein, the articles “a” and “an” are intended to include one or more items. Where only one item is intended, the term “one” or similar language is used. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.

The foregoing description gives only the embodiments of the present disclosure and is not intended to limit the present disclosure in any way. Thus, any modification, substitution, improvement or like made within the spirit and principle of the present disclosure should be encompassed by the scope of the present disclosure.